City won the Premier League – their fourth title in the last five campaigns under Pep Guardiola – in dramatic fashion on the final day of the season on Monday (AEST), coming from 2-0 down to beat Aston Villa 3-2 at the Etihad Stadium.
However, as has been the case at several grounds across the country in recent weeks, City's win sparked scenes of fans charging onto the pitch at full-time.
While the majority of the supporters celebrated peacefully, some fans were seen to have approached Villa goalkeeper Robin Olsen, who had to be escorted off the pitch by stewards.
Steven Gerrard subsequently confirmed that his goalkeeper had been "attacked" while City released a statement apologising to Villa and Olsen, promising a full investigation.
The incident follows on from a Nottingham Forest fan having been jailed for assaulting Sheffield United striker Billy Sharp at the end of a Championship play-off semi-final, while lower down the pyramid, Port Vale fans were involved in an altercation with Swindon Town players.
On Friday, Everton supporters ran onto the pitch to celebrate a 3-2 comeback win over Crystal Palace that secured their Premier League status.
It is a situation that former Manchester United and England defender Gary Neville is extremely worried by.
"This brilliant last 20 years, or 30 years, where we've brought the fences down in English football and the fans are respected and 99 times out of 100 they don't run onto the pitch because they enjoy the family environment, far more children coming to the game, far more women coming to the game," Neville said on Sky Sports.
"All of a sudden in this last few weeks, months, not just running on the pitch, which is a problem, but if you're attacking managers and players – what are you doing?
"Running on the pitch, they've won the league, they're delirious, I get that, but attacking the opposition players on the pitch – where has this come from, why is happening?
"I've got no idea, it's absolutely ridiculous."
It was a sentiment echoed by Neville's former Manchested United team-mate Keane, who is concerned by what may come next.
He said: "A player or a manager is going to be seriously injured. If you're mad enough to punch a player you're going to be mad enough to do something stupid like stab a player.
"I think people have come back after COVID and forgot how to behave themselves. Idiots, scumbags, disgrace. Absolutely disgraceful."